Pump



Jan. 19,` 1937. G. w. RAWLlNGs v 2,068,196

' PUMP Filed July 1o, 1935 2 sheets-sheet 2 w @V NNN mf A@ k v FMR/ m.

Patented Jan. 19, 1937 l PUMP George William Rawlings, Park Hill,

Kenilworth, England v Application July 1o, 1935 serial No. 30,606 InGreat Britain December 14, 1934 s claims. rc1. H4)

10 the contained 'volume of thetube is alternately 'increased anddecreased or is alternately increased or decreased and restored to itsinitial Y volume.

With pumps of the' said kind it is found that when used fordeliveringliquid at relatively high pressures andA under the same conditions ofoperation'a constant volume of delivery for each pumping cycle isvnotattained owing to the compression of the liquid or of air which mayhave entered the tube or of air occluded wit-hinthe S liquid. As aconsequence pumps of this kind have not been very successful whenutilized forv the injection of liquid fuel for direct fuel injectioninternal combustion engines and the present invention has for itsprimary object the provision of an improved liquid pump which retains.the simplicity ofpumps of the kind under rview but which at the sametime ensures the delivery of constant volumes of liquid ateach pumpingcycle 3l) under the same conditions of operation.

A further object of the invention is the provision of means whichensures an abrupt termination to the discharge thereby rendering thepump \parti cularly suitable for the injection ofl fuel in.

' 35 internal combustion engines of the direct Ifuel injection type. Y

The invention consists 'of an improved pump comprising a tube,means foreffecting an alternate flexing, bending or twisting of the said tube 40so as to engender a pumping effort by varying the contained volume ofthe bore of said tube,l a pumping chamber, a pump body having therein apassage placing thev said chamberin communication with a source ofsupplyand with a discharge line and with an orifice opening into thepumping chamber, valve means vfor controllingv the supply of liquid tosaid passage and the fdischarge of liquid -therefrom, a mercury'iillingfor saidl tube, free from air, a re'silientdiaphragm dividing theaforesaid pump'ng chamber from the tube and consequently from theadjacent end of the mercury column, said diaphragm normally occupying a.position in which the volume of the pumping chamber is slightly inexcess of the f5 maximum volume of liquid required to be ejecteddrawings which villustrate at a delivery operation and under theinuenceof the pressure generated in the tube, closing the aforesaid orice.

The invention will now be described with par-` ticular -reference to theaccompanying sheets of- 5 the invention in its application to' a liquidfuel injection pump for use with an internal combustion engine of t-hedirect fuel injection type.

Figure 1 is a vertical section lof the improved pump.V

. Figure 21s a composite fragmentary view illustrating diagrammaticallythe position occupied by the parts immediately prior to injection,I the15 portion of the pump containing the diaphragm referred to hereinbeforebeing shown on an enlarged scale.

Figure 3 is a similar view to Figure 2 but show- "ing the positionsyoccupied by the parts at the 0" completion of an injection. -Asillustrated in the drawings, the improved injection pump comprises acurved metal walled tube l of an elliptical shape in cross section, saidtube being closed at one end and having pivotal 25 connection adjacentto this closed end to the outer end of a lever 5 which is fulcrumedadjacent to its other end on a ball Abearing race' which is mounted on afixed spindle 1. This lever 5 is provided intermediatey the ends with' apro- 30 jection 5F which co-operates with a cam 8 mounted onl a shaft .9adapted to be rotated by the engine. The other end ofthe tube 4 to thatmentioned terminates in an enlarged portion' 4a having therein acentrally disposed aperture which 35 communicates with the bore in thetube 4 the said aperture .being closed by a removable plug l0. The borein the enlarged portion 4B has communication by way of a passage 4b withan inclined passage Iln formed in a body Il supported from 40 the baseI2 of the pump said passage IlEt opening into a. chamber Hb. The body'Il is provided with a cylindrical recess which is symmetricallydisposed relativelyfto the chamber Ilb but of greater diameter. Thewalls of the cylindrical' 45 recess are tapped for .the reception of ablock I3 having therein a vertically disposed passage I3, This passagel3l'communicates by way of a onewayv valve Il with a passage leading tothe discharge line I5 from a pump, hereinafter termed 50 the primarypump, which is not shown but which is generally 'similar to theinjection pump illustrated hereinbefore and which primary pump deliversfuel from a reservoir to the aforesaid injection pump. The liquid isSupplied. to the injection pump through a nozzle I 6 which has adischarge orice having a known coeiiicient of discharge so that byvarying the pressure of the supply as delivered by the primary pump thequantity of fuel supplied to the present pump,

.parts by a dished spring steel diaphragm I9 and the upper part of thesaid chamber I Ib is termed hereinafter the pumping chamber llc.

The lower part o f the chamber I Ib, the passage II, 4b' and the bore ofthe tube 4 are lled with mercury which is freed from air.

The volume of the pumping chamber IIc is slightly greater than themaximumquantity of liquid which is capable of being delivered at apumping cycle.

'I'he operation of the pump as shown in the accompanying drawings is asiollows:- l

Liquid is supplied at a controllable pressure b the primary pump to thepumping chamber II by way of the nozzle I6, the one way valve I4 and thepassage/A3. 'Ihe liquid is admitted to the pumping chamber IIc .duringthat part of the cycle when the engine driven shaft 9 is rotating thecani 8 from the initial position shown in Figure 3 to that showninFigure 2. During this ad' mission period the tube 4 is flexed by thelever 5 in such a manner that its `contained volume is increased thuspermitting the Vdiaphragm I9 to assume the position shown in Figure 2and thus providing capacity for the inlet of fluid to the pumpingchamber IIC.

The quantity of fluid supplied to the p pingv chamber IIc din-ing thisadmission pe d depends not only upon thev capacity so provided but alsoupon the pressure maintained by the primary pump and the coeiiicient ofdischarge of the nozzle I 6. When the further rotation of the shaft 9completes the revolution and brings the cam 8 to the initial positionshown in Figures land 3 the tube 4 is .permitted to resume its initialform whereupon its contained volume is decreased and the diaphragm I9 issubjected to the consequent pressure of-the mercury lling and visthereby constrained toeject theliquid from the chamber II, thisejection1 continuinguntil the diaphragm I9 abuts the face oi the blockI3 as shown in 4Figure 3 whereupon the ejection terf minates'abruptly.This ejection of the liquidv from the pumping chamber IIc is of coursethe injection of fuel to the engine.

.It will be `appreciated that under any given conditions of workingconstant quantities of liquid are` supplied to the injection pump andthat constant quantities of liquid are forced by the injection pump tothe fuel injector.

'Ihe tube .I may be filled with' liquids having a high bulk modulusother than mercury or with a plastic material provided of course thatthe liquid or plastic material employed is not subject to any solventorother undesirable action with the medium being pumped.

In a modification not illustrated a iiat diaphragm I9 maybe employed andthe lower end of theblock I3 given a concave formation.

It will vbe obvious that a battery of pumps may be operated from acommon vengine driven shaft 9. Y

What I claim isz- 1. A pump comprising a tube, means for effecting analternate flexing, bending or twisting of the said tube so as toengender a pumping eiort by varying the contained volume of the bore ofsaid tube, a pumping chamber, a pump body having therein a passageplacing the said chamber in communication with a source of supply andwith a discharge line and with an orifice opening into the pumpingchamber, valve means ior controlling the supply of liquid to saidpassage and the discharge of liquid therefrom, a mercury filling forsaid tube free from air.' a resilient diaphragm dividing the pumpchamber into two parts one of which is in communication by way of theaforesaid orice with the passage in the pump body and the other part ofwhich is in communication with the tube and is lled with mercury, saiddiaphragm normally occupying the position in which the volume `of thepumping chamber is slightly in excess loi! the maximum volume of liquidrequired to be ejected at a delivery operation and under the iniiuenceof the pressure generated in the tube closing the aforesaid orifice toeiiect an abrupt termination of a discharge operation.

2. A pump comprising a tube, a power source, means driven from saidpower source for periodically bending the tube so. as to engender apumping effort by varying/the contained volume of the bore of said tube,a pump' body, a pumping chamber formed in said pump body, a plug adaptedto flt within safd body and having therein a passage placing the pumpingchamber in communication with a source of supply'and with a dischargeline and with an orifice opening into the pumping chamber, valve meansVfor controlling the supply of liquid to said passage and the 'dischargeof liquid. therefrom, a mercury iilling for said tube,j and a resilientsheet steel diaphragm dividing the aforesaid pumping chamber into twoparts one of which is in communication by way of the aforesaid orificewith the passage in the plug and the other ofwhich is in communicationwith the tube and is filled by mercury, said diaphragm normally Ioccupying thepositionin which the volume of the pumping chamber isslightly in excess ofthe v `maximum volume of liquid required to beejected .at a delivery and under the influence of the pressure generatedin the tube closing with a snap action the aforesaid orifice in order toeiect an abrupt termination of the discharge.

3. A pump, according to claim 2, wherein the diaphragm' is dished andcoacts.with the flat end of theplug for the purpose of enhancing thespeed of closure of the orice by the diaphragm.

GEORGE WILLIAM RAWLINGS.

